Unit 5

• Inheritance is the transmission of genetic information from generation to generation
• A chromosome is a thread of DNA made up of a string of genes.
• A gene is a length of DNA that is the unit of heredity and codes for a specific protein. A gene may be copied and passed on to the next generation.
• An allele is two or more alternative forms of a gene.
• Fill in the blanks of this table:

  A) Deoxyribose

  B) Ribose

  C) thymine

  D) uracil

  E) two

  F) one

  G) nucleus

  
• In transcription the DNA is uncoiled by the enzyme RNA polymerase.
• In transcription free RNA nucleotides start to form an RNA strand using the DNA strand as a template. This can be done because of complimentary base pairing. In RNA you replace thymine with uracil. RNA polymerase is involved in the formation of RNA strand and uncoiling the double helix of DNA. The RNA strand elongates and seperates from the DNA template, and this strand is called messeger RNA (mRNA).
• A triplet of bases form a codon. Each codon codes for a specific amino acid. Amino acids link to form proteins.
• AUG is the start codon and UAA is the end codon
• Translation is when the mRNA leaves the nucleus to go and bind with the ribosome. Aside from mRNA there is also tRNA which have specific amino acids attached to them corresponding to their anti-codons. A tRNA molecule will bind to the ribosome, however the anti-codon MUST match the codon on the mRNA. Hydrogen bonds are formed, then the amino acids on the tRNA molecules form a peptide bond, polypeptide chain is eventually formed.
• Genes store the information that is needed, essentially the blueprint, for making polypeptides.
• A genotype is the genetic makeup in terms of the alleles present, it basically is the code for a specific phenotype.
• A phenotype is the physical/other features of an organism that is due to its genotype and environment.
• If a pair of alleles is neither completely dominant or recessive, then in a heterozygote they will both have an affect on the phenotype. We call this codominance
• A and B are both co-dominant in blood but both are also dominant to O.
• Polygenic inheritance is when a lot of genes contribute to a specific phenotypic characteristic, an example of this would be the genes that contribute to the pigmentation in human skin colour.
• The father determines the sex of the child.
• In pedigree charts, you use different symbols to show wether a person on the chart is: deceased, affected, or female or male.
• Mitosis is the division that produces genetically identical cells wherein the chromosome number is maintained by the exact duplication of chromosomes. It is used all throughout the body for things like cell repair and growth.
• Meiosis is the reduction division in which the chromosome number is halved from diploid to haploid.
• Haploid Gametes are made by meiosis and join together to form Diploid zygotes
• Fill in the blanks of the diagram:

  A) four

  B) pair

  C) seperate

  D) one

  E) daughter cell

  
• Continuous variation is influenced by genes and the environment.
• Discontinuous variation is caused only by genes.
• Mutation is change in a gene or chromosome, but generally have no or little effect on phenotype although rarely they do have a significant affect.
• A change in DNA affects phenotype by altering the sequence of amino acids in protein.
• Ionising radiation (mutagenes) increases rate of mutation. Similarly chemical mutagenes in tobacco also cause genetic mutations.
• Over-production: most organisms produce more offspring then will survive to reach adult hood
• Struggle for existence: populations typically don't increase rapidly in size so there must be considerable competition for survival between organisms.
• Natural selection is the greater chance of passing on genes by best adapted organisms (cz... yk they survive long enough to reproduce)
• The types of genetic mutations are: substitution, insertion, deletion, and inversion.
• Substitution is when a base is substituted by another.
• Insertion is when a base that shouldn't be there is inserted in between two other bases.
• Deletion is when a base is removed between two bases that should be there.
• Inversion is when the order of bases has changed with some swapping positions